Antenna testing shield



April 10, 1962 H. s. JONES, Jl R 3,029,430

. ANTENNA TESTING SHIELD Filed Aug. 26, 1960 2 Sheets-Sheet 1 Fig. 3

'INVENTOR HOWARD S. JONES BY 2 2% ma, @1211 15 We April 10, 1962 H. s.JONES, JR

ANTENNA TESTING SHIELD 2 Sheets-Sheet 2 Filed Aug. 26, 1960 INVENTORHOWARD S. JONES .72

BY Qfl 4.; ifh lz @I-V QLZ,

United States PatentOfilice 3,029,439 Patented Apr. 1%, 1952 r 3,029,430AN NNA'TESTING' SHIELD Howard S. Joues,.Jr., Washington, D.C., assignorto the United States of America as represented by the Secretary oftheArmy Filed Aug. 26, 1960, Ser. No. 52,313

V 2 Claims. (Cl. 343-703) (Granted under Title 35, U.S. Code (1952),sec. 266) The invention described herein may be manufactured and used byor for the Government for governmental purposes without the payment tome of any royalty thereon.

This invention relates generally to the testing of guided missile fuzes,,and more particularly relates to a device for coupling fuze antennas totest equipment under conditions approximating those of free space.

In the past, those engaged in the art of testing microwave fuzesutilizing antennas for sensing the proximity of a target have beenunsuccessful in simulating free U space conditions as the environmentfor the fuze under test. The reason for the failure of the prior art tocome up with a workable solution to this testing problem has been a lackof appreciation of the extremely com plex nature of conditions which amissile fuze encounters during its flight through space. Antennaleakage, skin currents, and far target signal return are among thoseconditions complexing the free space fuze environment.

This invention eifects a practicable solution to the above-mentionedproblem by providing a hood which surrounds the fuze under test andwhich contains therewithin antennas for coupling energy from the fuze totest equipment and thence back to the fuze. The hood is so constructedthat antenna leakage, fuze skin currents and far target return can beeffectively simulated and controlled.

Accordingly, it is an object of this invention to provide a device forsimulating free space conditions in a fuze undergoing operationaltesting. p

A further object of this invention is to provide for the coupling ofenergy from a microwave fuze to test equipment and back to the fuze fordetermining the fuze response under conditions of actual use.

.Other objects, advantages and features of the invention will beapparent from the following description considered together with thedrawings, in which:

FIG. 1 is a side viewof a space hood in accordance' with the invention.

FIG. 2 is a plan view of the space hood of FIG. 1. I i 50 FIG. 3 is asectional view taken through section line 33 of FIG. 1; and

FIG. 4 is a three-dimensional view of the space hood of FIG. 1, brokenaway in parts and with the fuze partially positioned therein.

In FIGS. 1, 2 and 3, a comically-shaped metallic spacehood is shown. Asshown in FIGS. 2 and 3, the interior of spacehood 10 is divided into aplurality of compartments by conductive partitions 19. Mounted along theedge of each of the partitions 19 is a metallic strip 20 for makingelectrical contact with the surface of the fuze. The strips 20 arepreferably of berylliumcopper--a springy alloy well suited for pressingsnugly against the fuze surface.

In FIG. 3 it can be seen that each compartment is lined with standardR.F. current absorbing material 21 and all but two of the compartmentsare filled with a standard microwave absorbing material 22. In one ofthe two compartments not containing material 22 there is secured atransmitting antenna and in the other diametrically opposite the firstthere is mounted a receiving antenna 17.

The bottom of the spacehood, upon which the nose of crating at microwavefrequencies.

ing members 13 are equally spaced about the circumference of ring 12 todesignate the proper position of the fuze receiving antennas when thefuze is seated in ring 12. i

In FIG. 4 a sonically-shaped fuze 18 having transmitting antennas 14 andreceiving antennas 16 along the surface thereof is shown partiallylowered into spacehood 10. The positioning apparatus illustrated inFIGS.

1 and 2 has been omitted here for clarity. Fuze transmitting antenna 14'is centrally disposed in the compartment containing hood receivingantenna 17, while fuze receiving antenna 16 is similarly disposed in thecompartment containing hood transmitting antenna 15. The other fuzeantennas 14 and 16 are centrally located in the compartments filled withmicrowaveabsorbing material 22. The hood antennas 15 and 17 are inparallel relationship with'their associated fuze antennas 16' and 14'and are inverted with respect thereto to impart the proper phaserelationship to the coupled microwave energy. v

In the testing of the fuze, energy is usually fed into a matchedthree-way junction and distributed equally to the transmitting antennas14 and 14. The radiated energy picked up by the hood antenna 17 is fedinto test equipment including delay means and is then fed back to thetransmitting antenna 15. Fuze antenna 16' will pick up the returnedenergy and feed it to the fuze detonator whose functioning is to betested by additional equipment. It is to be understood that since thefuze and its associated testing equipment are purely conventional andform no part of the present invention no showing thereof in the drawingsis made.

The spacehood of the present invention thus effectively decouples thefuze antennas from each other by restricting the energy radiatedtherefrom to the hood compartments. Up to 60 db decoupling between adjacent fuze transmitting and receiving antennas has been achieved whilethe noise level of the fuze receiver detector has been reduced abouteight-fold over that of the prior art devices. The highly efiicientcoupling between the fuze antennas and their associated hood antennashas been found to be optimized at a spacing therebetween of about 1.75inches for a typical fuze op- However, despite their close relativeproximity, no increase in the voltage standing wave ratio of either thefuze or hood antennas is observable.

Although one specific embodiment of the invention has been described, itshould be realized that various modifications could be made. Forexample, the number of antennas could be varied and the shape of thespacehood changed to meet the requirements of the particular fuze to betested.

I claim as my invention:

1. A device for use in conjunction with means for testing the operatingcharacteristics of a fuze having sending and receiving antennas mountedthereon, said device comprising: a hood having a conical shape, meansfor securing said fuze within said hood, two antennas integral with thehood and mounted in the interior thereof such that one of said hoodantennas is in coupled relationship with one of said fuze sendingantennas and the other of said hood antennas is in coupled relationshipto one of said fuze receiving antennas, the interior of said hood beingdivided into a plurality of compartments equal in number to the numberof fuze antennas, each compartment surrounding one of the fuze antennas,

the hood antennas being mounted within two of said compartments.

2. The device set forth in claim 1 wherein those compartments not havinghood antennas mounted therein are lined with microwave absorbingmaterial, and the edges of said plurality of compartments are providedwith conductive strips which are adapted to be flush with the surface ofsaid fuze when the fuze is secured in place by said securing means.

References Cited in the file of this patent UNITED STATES PATENTS2,490,782 Collup Dec. 13, 1949

